Drilling implement



Patented Feb. 27, 1940 UNITED STATES PATENT OFFICE...

of Massachusetts Application July 23. 1935, SeriaiNo. 3am

Renewed July 15, 1939 15 Claims. (-01. 255-64) My invention relates todrilling implements, and more particularly, though not exclusively, torock drill bits of the detachable type.

In the drilling of rock it is found that one o the most seriousimpediments to long continued drilling with any tool is the wear whichresults in a blunting of the outermost portions of the tool. A furtherdifliculty in drilling rock lies in the fact that with conventionaldrill bits there is 10, a rapid loss of gauge, and a consequent need,particularly when the gauge is lost very rapidly, of starting a. holemuch larger than the desired diameter of the bottomed hole.- It isfurther I found in connection with detachable bits that 16 resharpeningis a substantial problem, and where resharpening can be accomplishedwholly by a grinding operation, or a series of grinding operations, and"forging and retempering can be avoided, it is highly advantageous.[Still another 20 dimculty in connection with rock drilling resides inthe fact that with certain forms of tool, rifling of the hole is likelyto occur.

It is an object of the present invention to provide improved rockdrilling implements which 95 will avoid as many of the 'diflicultie'smentioned as possible, while possessing the advantage of easyresharpening. It is another object, of the invention to provide animproved rock drilling implement in which the different edges shalleach'be caused to do a maximum amount of work, whereby the force of theblow may be concentrated on as small alinear extent of edge aspracticable, with resultant greater penetration. It is still anotherobject of my invention to provide an 35 improved rock drilling apparatusin which rifling may be'prevented. It is yet another object of myinvention to provide an improved rock drilling apparatus in whichreaming of the hole may be most effectually accomplished. It a-still 40further object of my invention to provide an improved rock drillingimplement which may bev sharpened in an extremely simple manner with theuse of a single grinding wheel. Other'objects and advantages of theinvention will hereinafter more fully appear.

In the accompanying drawing, in'which three forms of embodiment which myinvention may I said view being taken at right angles to the view Fig. 3is a front end view of the bit shown in Figs. 1 and 2. I

Fig. 4 is a view corresponding to Fig. 2, showing another illustrativeembodiment.

Fig. 5 is a front end view of the bit of Fig. 4. 5

Fig. 6 is a view similar to Fig. 1, showing a third illustrativeembodiment of the invention.

Fig. 'l is a central section at right angles to the plane of thesectional portion of Fig. 6, through the bit of Fig. 6. 10

Fig. 8 is a front end view of the bit of Figs. 6 and 7.

Referring first to Figs. 1 to 3 of the drawing, it will be observed thata drill bit, generallydesignated I, is provided with an internallythreaded socket 2 by meansof which it may be secured during drilling tothe forward end of a threaded shank. Obviously, any other form ofconnection with a shank might be employed without departing from thespirit of the invention. 2 The bit'l is generally cruciform in front endelevation; and comprises a pair of relatively ,narrow, oppositelydisposed wings 3 and 4,'and

a pair of relatively wide, oppositely disposed wings 5 and 6 arranged atright angles to the wings 3 and 4. The spaces I between adjacent wingsprovide clearance for the ready escape of the cuttings produced when thebit is in use. The wings 3 and 4 support a diametrically extendingcutting edge 8, which is of less than the full diameter of the bit andwhich terminates, as at the points 9, short of the ends of the wings 3'and 4; and'inclinedsurfaces III of triangular shape extend'from theextremities of the edge 8 to the periphery ll of the bit at the endsofothe wings 85 3 and l. The edge 8 is formed at the intersection ofrelatively inclined'planes l2 and i3 bounding the forward end of thewings 3 and 4. The wings 5 and 8 have their forward surfaces formed byinclined planes I4 and I5 extending from- 40 lines of intersection withthe planes l2. and i3 forwardly and outwardly toward the periphery ofthe bit. These surfaces may extend wholly to the periphery of the bit,or only partially thereto, as at; It, thereby to provide reaming orchopping edges, and there may be formedvery narrow segmentalsurfaces I]at the centralpor-- tions'of theends of the wings 5 and 8. As will benoted in Figs. 1 and 2, the surfaces l1 and the cutting edge 8 maydesirably be located inthe same transverse plane perpendieular to theaxis of the bit. It is not imperative that this arrangement exist, butexcellent results arm-attainable with this relatively equal distributionof the. force of the blow on a uniform plane of'advan'ce} A u.

cleansing fluid delivery passage l9 opens through the forward surface ofthe bit in the angle between one of the pairs of wings, herein 4 and 5.

It is important to note that although the rearward ends of the inclinedsurfaces 10 lie back of the foremost transverse plane of the bit, theover-all diametric dimension in the central line of the wings 3 and 4 isequal to, though set back from, the over-all dimension of the bitbetween the most remote portions of the surfaces H. Accordingly, norifling of the hole is possible.

The mode of operation of this form of the invention will be readilyunderstood. As the bit is mounted upon the end of a percussivelyactuated and rotated shank, the edge 6 will cut away the rock in acircle of somewhat smaller diameter than the over-all diameter of thedrill bit. The reaming or chopping edges I! will, however, not onlyconcurrently maintain the full diameter of the hole by chopping away andinwardly breaking the stone about the periphery of the hole, but willalso break loose the stone between the periphery of the hole and thecircular zone cut out by the edge 8. Accordingly, greater penetra tionby the edge 8 will be possible, and the reaming edges not only will because to perform their function of maintaining the diameter of the hole,but will also break away the stone in a substantial annulus disposedinwardly of the periphery of the hole. The extremities of the wings 3and 4 being in the diameter of the bit at the periphery of the hole,will very effectually prevent any tendency to rifle, and will maintainthe bit at all times central of the hole being drilled. The formation ofthe inclined surfaces In will not be found to reduce the effectivenessof the bit materially, because the reaming or chopping edges will removethe stone which the deliberately removed potential extremities of-thecutting edge 8 would have cut away, and indeed the lessened totalcutting edge length will be found instead to permit a greater unitcutting effect throughout the length of the cutting edge, and a veryefficient drilling.

With reference to the species shown in Figs. 4 and 5, it will beobserved that the wings 3 and 4 replace the wings 3 and 4 of the speciesof Figs. 1 to 3, but that aside from the difference in the formation ofthe extremities of wings 3 and 4 there is essential similarity betweenthe two bits. The wings 5 and 6, the edges and surfaces IB and ILtheplane surfaces l2, l3, l4 and I5, and the cleansing fluid conductingpassage l9, are essentially the same. The surfaces extending from thepoints at the extremity of the cutting edge 8 are, however, notrelatively conical, as in the bit of Figs. 1 to 3, and of an extentreaching from the extremities of the cutting edge completely to theperiphery of the bit. Instead there is provided at the end of each wing3 and 4' a relatively plane triangular surface 2| extending from the endof the edge 3 to a line 22 extending across the outer edge of the wingfrom the outermost rearmost points in the surfaces [2' and I3; and achopping or reaming surface 23 of segmental form, and advantageously ina plane extending substantially at right angles to the axis of the bit,is provided at the end of each wing. It will be noted, therefore,thatthe surfaces 23 provide additional small chopping or reamingsurfaces to the rear of the edges l8 and surfaces l1; and these serve tomaintain clean and smooth the bore of the hole. Because of theirposition to the rear of the forward end of the bit, they do not carrythe brunt ol the cutting or reaming action, and therefore may be ofreduced size. They contribute nevertheless to the beneficial working ofthe bit. In this form of the invention, as in the embodiment of Figs. 1to 3, the overall dimension of the bit in the central line of the Wings3 and 4 is equal to the over-all dimension in the direction of thecentral line of the wings 5 and 5, so that the surfaces I1 and 23 attheir outer edges lie substantially equal distances from the axial lineof the bit. The surfaces 2| need not necessarily be plane, and thesurface 23 need not necessarily lie in a plane extending at right anglesto the axis of the bit. The mode of operation of this bit requireslittle further explanation. As the edge 8 chops away the stone occupyingthe central portion of the desired line in advance of the hole, theedges l6 and surfaces I'I ream the hole and the rearwardly disposedsurfaces 23 keep the hole smoothed up and truly round. Referring now tothe bit of Figs. 6, 7 and 8, it

will be noted that this bit comprises wings 3 and 4 of relativelynarrowwidth, and wings 5 and 6 of relatively greater width, the wings 3"and 4 being alined and the wings 5 and 6' being alined, the wings 3 and4 being at right angles to the wings 5 and 6 Clearance is provided at lfor the escape of cuttings. The wings 3 and 4 have at their forward endsurfaces 2| and 22 extending from the lateral edges of the wingsforwardly to intersect in radial cutting edges 3. These cutting edgesextend from the outer extremities of the Wings 3'' and 4'' toward thecenter of the drill bit, but terminate a substantial distance short of.the axis of the bit. The Wings 5' and Ii" have their forward surfacesformed by an arcuate surface 24, formed by the action of a grindingwheel presented to the bit or to which the bit is presented, so that thewheel forms the surface 24 at a single grinding operation. The surface24 is both arcuate transversely of the bit in the direction of the wings5 and I, and also arcuate, as indicated at 25 in Fig. 'I, in a directionat right angles to the central line ofthe wings 5 and 6". Thus it may besaid that the surface 24 is arcuate with respect to axes disposedrelatively at right angles to each other, such axes lying in the centralplanes of the wings. As a result of the appropriate selection ofagrinding wheel so that its diameter and the curvature of its peripherytransversely are each proper for the purpose to be accomplished, it ispossible td cause the surfaces 24 either to produce smooth reaming edgesin the plane of the forward end of the bit or to provide, narrow arcuatesurfaces 25, as illustrated, at the ends' of the wings 5" and A centralcleansing fluid supply passage 2l is provided through the bit. It willbe notedthat the inward extent of the cutting edges 8' is determined bythe width of the grinding wheel which forms .the surfaces 24, therebeing shoulders 28 at the inner ends of the wings 3" and 4 iifline withthe side surfaces'of thewings i and i". From this it will beobvious'that desirably the width of the grinding wheel should be thesame as the width of the wings 5 and I". It will'be obvious from whathas been pointed out that this bit will difler materially from the bitsof Iflgs.

-1to3and4and5inthatthecuttingedges 8" are disposed at the outer ends ofthe wings and spaced at their central portion, whereas the edges I andl" extend continuously through the central portion of their respectivebits, but ter-r minate short of the ends of the wings which support Inthis form of the intuition. how- 5 ing from its spirit or the scope ofthe appended ever, as in the other bits described, there is areducedover-all length of cutting edge as compared with standard bits,and a greaterunit cutting effort at each point in the cutting edge.Moreover, the over-all dimension in the central line of the wings 3 and4 is the same as the over-all dimension of the wings 5 and 6 The mode ofoperation of this form of the invention will be readily understood, andit will be noted that the edges 8 will cut away the stone along linesextending radially of the desired hole, while the slightly blunted edgeson the reamin wings 5 and 6 will provide constant clearance at theperiphery of the hole and reduce the burden upon the outermost ends ofthe edges 8.

The central portion of the hole will be broken away as a result of theshocks and the breaking inward of the stone at the inner ends of theedges 8.

From the foregoing description, it will be obvious that I have providedseveral highly eflicient, rugged, fast-cutting, readily resharpeneddrill bits, each possessing individual advantages, and all possessingcommon advantages of'ease of resharpening, maintenance of full diameterof the drill hole, maximum energy per unit of cuttingedge length, andaccordingly fast cutting. All may also be used on solid steels.

While I have in this application specifically described three formswhich my invention may assume in practice, it will be understood thatthese forms are shown for purposes of illustration, and that theinvention may be modified and embodied in various other forms withoutdepartclaims. I

What I claim as new and desire to secure by Letters Patent is:

1. A drill bit having Wings disposed in alined pairs at right angles toeach other, chopping or reaming edges at the outer extremities of thewings of one pair, and radially extending cutting edges supported by thewings of the other pair and terminating short of the outer ends of thelatter wings.

2. A drill bit having wings disposed in alined pairs at right angles toeach other, chopping or reaming edges at the outer extremities of thewings of one pair, and radially extending cutting edges supported by thewings of the other pair and terminating short of the periphery of thebit, the over-all dimension transversely of the bit of said lastmentioned pair of wings being equal to the over-all dimensiontransversely of the bit I of said other pair of wings.

3. A drill bit having wings disposed in alined pairs at right angles toeach other, chopping or reaming edges at the outer extremities of thewings of one pair, and radially extending cutting edges supported by thewings of the other pair and terminating short of the periphery of thebit, the over-all dimension transversely of the bit of said lastmentioned pair of wings beingequal to the over-all dimensiontransversely of the bit of said other pair of wings, and said lastmentioned pair of wings having segmental chopping edges at theiroutermost ends.

4. In a drill bit, a pair of chopping edges, a cutting edge, and anotherpair of chopping edges disposed to' the rear of said'first mentionedchopping edges. 1 5. In a drill bit, cutting and chopping edges at.. theforward end of the bit, and further chopping means disposed to the rearof the forward end of said bit. I

' a pair of -respective outer sides whose axis coincides with the bitaxis and at the1r respective inner sides by'a surface of revolution 6.In a rock drill bit, radially extending cutting means and associatedreaming means arranged in different quadrants from said cutting meansand formed at the opposite extremities of a surface of revolutioncurving at its central portion arcuately with respect to axes at rightangles to each other and having the axis from which it is generatedahead of the bit.

7. In a rock'drill bit, pairs of wings arranged at right angles to eachother, cutting edges at the outer ends of the wings of one pair, and.reaming or chopping edges at the outer extremities of the wings of theother pair, the forward face of said last mentioned wings being concaveboth longitudinally and laterally.

. and having mutually diametrically opposite portions carrying choppingedges disposed in their entireties to the rear of the forward end ofsaid bit.

bit and spaced apart by the full diameter of said 9. In a rock drillbit, a shank terminating a plurality of radially extending wings ofsubstantially equal radial extent, arranged in pairs,

the wings of each pair diametrically opposite each other and saidpairsat right angles to each other, a pair of diametrically oppositelydisposed chopping portions formed at the outer extremities of the wingsof one of said pairs and extending circumferentially of the bit, and, ina line midway between said portions and ina plane including the axis ofsaid bit and midway between the sides of the wings of the other pair andat opposite sides of the axis of the bit, alined. cutting-edge portionseach of a length materially less than the radius of the bit whereby theyterminate short of the outer ends of, the wings midway between i thesides of which they are disposed.

10. In a rock drill bit, reaming means including a pair of diametricallyoppositely disposed, narrow, arcuate chopping portions lying in a commonplane perpendicular to the bit axis and bounded on their respectiveouter sides by a surface of revolution whose axis coincides with the bitaxis and at their respective inner sides by a surface of revolutionwhose axis is perpendicular to said bit axis and which is of at least asgreat radial dimension at the axial line of the drill bit as at anypoint therein.

ii. In a rock drill bit, reaming means including.

diametrically oppositely disposed, arcuate chopping portions lying atthe periphery of the forward end of the bit and bounded on their by asurface of revolution whose axis is perpendicular to said bit axis andwhose generatrix is curved, and of maximum radial dimension with respectto its axis in the line of the drill bit axis, and of flatter curvaturethan the curve of said arcuate chopping portions.

12. In a rock drill bit, pairs of wings arranged at right angles to eachother, alined cutting edges on the wings of one of said pairs, saidedges spaced by the fullwidth of the wings of the other pair, andreaming edges at the outer extremities of the wings of the latter pairformed between the'p'eripheral surface of said wings and a surface ofrevolution having its axis parallel to said cutting edges and forward ofthglatter.

13. In a rock drill bit, pairs of wings arranged at right angles to eachother, alinedcutting edges on the wings of one of said pairs, andspacedarcu- 75 ate chopping edges at the opposite extremities of the otherpair 0! wings arcuate only in front elevation, the forward face of saidbit bounded primarily by two planes forming a dihedral angle whose edgecoincides with said cutting edges and a surface of revolution whose axisis paral1l to said edges and forward of the same.

14. A drill bit comprising a shank terminating in a plurality ofradially extendingwings of substantially equal radial extent, said wingscarrying edges disposed alternately substantially perpendicular to theaxis of said bit and struck on arcs being cut back arcuately so that thecentraiporarouse tion of said bit is on a level with the bases of saidwedge-shaped supporting portions.

15. A rock drill bit having four wings at its forward end arranged inrectangular relation to each other, two of said wings carrying arcuatechopping edges substantially at the periphery of the bit and havingtheir forward surfaces and the portion or the front end of the bitbetween them 'formed upon a continuous concave and the other wingscarrying wedge-shaped supporting portions terminating in radial cuttingedges, the depth of such concave such that the wedgeshaped supportingportions may be ground bya wheel within said concave, and said concaveconformed to a surface of revolution whereby the same may be ground byradial presentation of the bit to the periphery of a wheel.

PAUL H. NAST.

